Adjustable crown roll



Dec. 15, 1964 HORNBOSTEL 3,161,125

ADJUSTABLE CROWN ROLL Filed Feb. 15. 1961 Fzga 1 INVENTOR. Lloyd Hornhas is United States Patent (Rice 3,161,125 ADJUSTABLE QROWN ROLL LloydHornbostel, Beioit, Wis, assignor to Beloit Iron Works, Beioit, Wis., acorporation of Wisconsin Filed Feb. 15, 1961, Ser. No. 89,527 5 Claims.(Cl. 100155) The present invention relates broadly to roll structures,and is more particularly concerned with a new and improved rollconstructed to counteract the tendency of the roll axis to deflect inresponse to a load applied to the roll.

The instant invention is of utility in various arts, however, it isparticularly useful in the paper making art and will accordingly bedescribed particularly in connection therewith. In paper machines thereare numerous types of rolls of substantial size which are subjected toloads tending to deflect the rolls centrally. Illustratively, wirereturn rolls in a Fourdrinier paper machine are subject to a loadtending to effect central deflection thereof by reason of the weight ofthe rolls themselves, the weight of the Fourdrinier wire carried by therolls, the tension on the Fourdrinier wire, and in the case of a drivenroll, the force component resulting from the reaction or resistance ofthe wire itself to the driving force. Such forces tend to deflect theroll downwardly in the middle, and this results in an undesirableguidance of the traveling wire, which condition has been foundadvantageous to avoid by counteracting the tendency for downwarddeflection of the return roll by one means or another.

In addition, in press couples, calender stacks and the like the webpasses through a nip between a pair of superimposed rolls whereat thenip is subjected to pressures. The pressures applied at the nip tend toload the lower roll and deflect the same centrally downwardly. Thisdeflection results in an undesirable application of forces across thenip, and other undesirable operating features. It has accordingly beenthe practice to correct such deflection in paper machines by ferowningthe lower roll. However, the crowning of a roll requires accurate andexpensive finishing of the roll surface so as to obtain a slightlygreater roll diameter in the central portion of the roll. As well, suchcrowning is carried out on the basis of a predetermined set of forceconditions, and may not be satisfactory for operation under a differentset of force conditions. Accordingly, crowning of rolls often does notafford satisfactory operation for many different types of conditions. i

In other arts related to paper machines, exemplified by the coating ofpaper or fabrics with plastic materials, pressure or calender rolls arealso used. In addition, paint 3,l5l,l25 Patented Dec. 15., 1964centrally thereof. Of course, the shell and shaft are coaxially spacedso that when a lifting force is applied to opposite ends of the shaftmeans, the shell and shaft do not initially contact and the shelldeflects generally centrally of its restrained opposite ends.

It is accordingly an important aim of the present invention to providean improved roll structure.

Another object of the instant invention is to provide an improvedstructure for a roll whose axis is subject to deflection in response toa load applied to the roll, by supporting a roll shell in coaxiallyspaced relation upon shaft means mounted in movable bearing meansadjacent the opposite ends thereof and by journaling opposite ends ofthe shell in fixed bearing means, a lifting force then being applied tothe bearing means for the shaft means to deflect the shell generallycentrally thereof.

A further object of this invention is to provide a novel combinationcomprising a roll shell having normally a central deflection, fixedbearings rotatably mounting the roll shell, shaft means for the rollshell having shaft portions extending outwardly from the opposite endsthereof, support means contacting the shaft means and the roll shellinwardly of the opposite ends thereof and normally maintaining the shaftmeans and shell in coaxially spaced relation, and means for applyingforces to the shaft portionsand through the support means therebyrelieving the normal deflection.

Other objects and advantages of the invention will become apparentduring the course of the following description, particularly when takenin connection with the accompanying drawings.

In the drawings, wherein like numerals designate like parts throughoutthe same:

FIGURE 1 is a diagrammatic illustration showing two lower rolls of astack of rolls, illustrating in somewhat exaggerated form the manner inwhich such rolls may be deflected during the specific correlation amongthe essential control factors in a calender stack of the prior art;

FIGURE 2 is an elevational view of one form of roll assembly constructedin accordance with this invention, parts thereof being shown in sectionand otherparts diagrammatically; and

FIGURE 3 is a view along the lines of FIGURE 2, but showing anotherarrangement of support means between the shaft and roll shell.

mixing roll systems or the like are subjected to a build a up of forcesin the central portion of the pressure hips,

which tend to cause central deflection of the rolls and result innon-uniform and/or other undesirable conditions across the width of suchpress nips.

The instant invention affords a simple and unique roll structure for aroll subject to a load tending to cause deflection of its axis. In thepresent roll structure the crowning of the roll may be varied withoutrebuilding the roll or refinishing the surface thereof. Instead, thecrowning of the roll is effected by mounting a roll shell in fixedbearings at the opposite ends thereof, by supporting the shell inwardlyof the opposite ends thereof upon shaft means, and by applying anupwardly directed force to bearing means receiving opposite ends of theshaft means. Since opposite ends of 'the shell are restrained againstvertical movement by the fixed bearing means and since between oppositeends of the shell said shell is supported by the shaft means, forcesapplied to opposite ends of the shaft means are transmitted through thesupport arrangement for the shaft to deflect the same generallyReferring first to FIGURE 1, there is shown a bottom portion of acalender stack, indicated generally by the reference numeral 10,andcomprising a king roll 11 at the bottom mounted on suitable bearings12 and 13 which are in turn firmly secured to a fixed mounting such as afloor F. Immediately above the king roll 11 is a calender roll 14 whichin turn is mounted for rotation in bearings 15 and 16.' Actually, theroll 11 is provided with a left hand stub shaft or shaft element 11arotatably received by the left hand bearing 12, and a right hand stubshaft 11b which is rotatably received by the right hand bearing 13. Theroll 14 is also provided with a left hand stub shaft 14:: which isrotatably received by the left hand bearing 15, and a right hand stubshaft 14b rotatably received by the right hand bearing 16.

As will be noted, the centroidal axis X-ll for the roll 11 is deflecteddownwardly below a horizontal or center line C-il at the middle of theroll 11 (which straight line C-11 is the unloaded rolls normalcentroidal axis) and.

above the outer extremities of the roll 11, and the bottom surface ofthe roll 11 is downwardly bowed still a greater distance D-11. Theamount of operating crown R-ll depends upon the amount of original crownformed on the roll 11 and the total weight of the calender stack ofrolls 14, etc. mounted thereabove. As will be appreciated, if it isdesired to operate a calender with substantially no operating crown(R-ll) in the king roll 11, the initial crown of the king roll 11 andthe total weight of the calender rolls 14, etc. are correlated so as toobtain substantially no operating crown. If, however, it then becomesdesirable to make a change in the operation of the prior art calender byusing less calender rolls in the stack, then a greater operating crownR-11 will be obtained. This may possibly result in an undesirablepressure distribution at the portion of the web W-l passing through thenip N-1. The same is true with respect to variations in load which maybe applied to any other crowned roll in a paper machine or other device.

In many of such prior art devices, the crown initially formed on theroll being subjected to the load is just sufficient to permit the rollto deflect in response to this predetermined load to such an extent thatthe roll presents a substantially flat (usually horizontal) nip definingsur face. It will be appreciated that any variation from suchpredetermined load will, however, necessarily result in a deviation fromthe desired flat or level contour of the operating surface or nipdefining line of the roll (herein designated 11c).

Referring now to FIGURE 2, there is shown and generally designatedtherein by the numeral 20 a roll assembly effective to overcome theproblems herein discussed. The roll assembly 20 comprises a roll shellor roll member 21 having a relatively large diameter main body portion21a and reduced diameter end portions 21b and 21c journaled in bearingmeans 22 and 23, fixed as shown to a floor or the like F-l andconstructed essentially identically. The description of one bearingmeans will accordingly sufiice for the other, and it may be seen thatthe bearing means 22 comprises a housing 24 mounting therewithin innerand outer races 25 and 26 receiving therebetween ball means 27.

Forming a part of the roll assembly 20 and providing the means forbowing the roll shell 21 or for relieving any central deflection thereincaused by its own weight or other factors is shaft means 30 having amain body portion 30a and reduced diameter end portions 30b and 300extending outwardly from opposite ends of the shell end portions 21b and210. Of course, the shaft means 30 could be of uniform diameterthroughout, but in any event the roll shell 21 is maintained incoaxially spaced relation with respect to the shaft means 30 by supportmeans 31 which may take the form of an annular collar, as shown, securedto the shaft body portion 30a. It may be found that for certainapplications the support means 31 may be provided by self-aligningbearing means afi'ixed in any desired manner to the shaft, butregardless of the particular construction of the support means 31, suchmeans as appears in FIGURE 2 is located centrally of opposite ends ofboth the roll shell 21 and shaft means 30. The support means 31 not onlynormally maintains the shell and shaft in the coaxially spaced relationillustrated, but functions additionally as force transmitting means torelieve deflection in the manner to be hereinafter described.

The end portions 30b and 36c of the shaft means 30 are journaled inseparate and independent non-fixed or movable bearing means 35 and 36,which as illustrated are of the conventional type, whereas the bearingmeans 22 and 23 for the roll shell 21 are desirably self-aligning, asillustrated. The bearing means 35 and 36 each comprises a housing 51mounting therewithin inner and outer races 51 and 52 receivingtherebetween ball means 53. Naturally, the latter two bearing means neednot be constructed in the precise manner shown, however, such 4 bearingmeans are positioned along the shaft end portions 30b and 300essentially in the locations indicated.

The shaft means 30, depending upon the particular application in whichit is employed, may be positively driven by motive meansdiagrammatically shown and indicated by the numeral 40, and in sucharrangement the roll shell 21 is thus driven through a rigid connectionwith the driven shaft means 30 (via the force transmitting means 31which is drivingly connected to the shell 21 due to friction pressureengagement therewith or by being welded thereto-the shell may be shrinkfit over the member 31 so that the member 31 presses into the innersurface of the shell 21, with the outer surface of the shell 21 beingground to a cylindrical shape). On the other hand, if employed in apress couple or in another environment wherein the roll shell 21 is innip-defining relationship with another roll, the driving force may besupplied by said other roll. Likewise, the roll shell 21 and connectingshaft means 30 may be driven by a traveling band moving thereover.

It has been noted hereinabove that the shaft means 30 may be of uniformdiameter throughout the length thereof and need not be provided with arelatively greater diameter body portion 30a. However, it is criticalthat the inner diameter of the shell end portions 21b and 21a and theouter diameter of the shaft end portions 30b and 300 surrounded by theshell end portions be so sized as to provide an adequate annular gap orspace 41 therebetween. The reason therefor is believed now apparent andwill be quite clear as the description continues.

In order to how the shell member 21 or to relieve any central deflectiontherein caused by its own weight or other factors there is applied tothe shaft end portions 30b and 30c generally upwardly directed forces inthe nature of lift. Such forces may take numerous forms, and for thisreason the force applying means are indicated diagrammatically byarrows, to which the numerals 42 and 43 have been applied. Desirably,the lifting forces are applied to the non-fixed bearing means 35 and 36,and the means for applying such forces can be fluid actuators of eitherthe pneumatic or hydraulic type. It is known that such fluid actuatorsprovide a continuous resilient force, and they are thus separate andindependent means for selectively positively displacing the bearings 22,23 and continuously resiliently urging such bearings 22, 23 upwardly.

Upon the application of lifting forces to the shaft end portions 30b and30c through the bearing means 3.5 and 36, such forces are transmittedthrough the shaft body portion 30a and support means 31 to the bodyportion 21a of the roll shell 21. Since the end portions 21b and 21c ofthe roll shell 21 are restrained against vertical movement by the fixedbearing means 22 and 23, the applied forces to the shaft end portionshave the effect of lifting and thereby deflecting the shell body portion21a generally centrally and for a distance outwardly to the restrainedopposite ends thereof. Generally stated, the maximum bowing or crowningachieved depends not only upon the magnitude of the forces applied andthe strength of the materials, but upon the extent of the annular gaps41 between the shell end portions 21b and 21c and the portions of theshaft ends 30b and 300 surrounded thereby. In other words, it isconceivable that the roll shell could be deflected, bowed or crowneduntil there is contact between the shell and shaft end portions in theregion of the annular spaces or gaps 41. In any event, by applyinglifting forces with such fluid actuators indicated diagrammatically at42 and 43 to the shaft means 30 in the roll assembly illustrated anddescribed, the load applied to the shell is continuously counteractedand normal deflection of the roll shell 21 is effectively relieved. Itis also apparent from the drawing and the foregoing description that inthe application of such lifting forces at 42 and 43 the inherentresistance to deflection in the shell 21 yields to the inherentresistance to deflection of the shaft 30, so that a deflection changeoccurs substantially in the shell 21 otherwise normally deflected inresponse to the load an plied thereto. The shell 21 is shown bentinFIGURES Z and 3 while the shaft means 39 is straight. This is forreasons of illustration, although the shell normally will bend moreinasmuch as it has less total stiffness but it will of course beunderstood that some bending occurs in the shaft means 30 andparticularly at the ends 3% and 3% which are of lighter weight than thecenter 30a.

It may be found under particular circumstances that the normaldeflection in the roll shell 21 is not uniform outwardly of the verticalcenterline thereof, and accordingly, the application of deflectionrelieving forces through the centrally located support means 31 may notproduce the results desired. For this purpose, and as appears in FIGURE3, there is provided at equally spaced locations from the verticalcenterline of the shaft means 30 a pair of auxiliary support means 44and 46. The latter means may take the form of annular collar members incontact with both the outer diameter of the shaft body portion 30a andthe inner diameter of the shell body portion 21a. As appears, thesupport means 44 and 46 may be constructed identically to'the supportmember 31 of FIGURE 2, and would therefore desirably be secured to theshaft portion 30a. In this manner, forces applied at -42 and 43 to thebearing means 35 and 36, and transmitted through the central supportmeans 31 to the roll shell body portion 21a, are uniformly distributedthrough the auxiliary support means 44 and 46 to assure that thedeflection curve is properly matched and better flexure controlattained.

It will of course be understood that modifications and variations maybeetfected Without departing from the spirit and scope of the novelconcepts of the present in vention.

I claim as my invention:

1. Apparatus comprising, a roll shell having normally a straight linecentroidal axis that develops normally, a central deflection in responseto a load applied to the shell, fixed bearings rotatably mounting theends of said roll shell, shaft means for the roll shell having shaftportions extending outwardly from the opposite ends thereof, supportmeans between said shaft means and said roll shell inwardly of theopposite ends thereof and normally maintaining said shaft means and saidshell in coaxially spaced relation, and movable fluid actuated resilientmeans for applying a lifting force to each of said shaft portions inopposition to the restraint on said roll shell provided by said fixedbearings continuously counteracting said load to relieve the normaldeflection in said shell, said roll shell having a given inherentresistance to deflection and said shaft means having a substantiallygreater inherent resistance to deflection, and said given inherentresistance to deflection of the shell yielding substantially to saidgreater inherent resistance of the shaft means.

2. Apparatus comprising, a roll shell having a given inherent resistanceto deflection and havingin unloadedcondition a straight-line centroidalaxis that develops normally a central deflection in response to a loadapplied to the shell, fixed bearings rotatably mounting the ends of saidroll shell, shaft means for the roll shell having shaft portionsextending outwardly from the opposite ends thereof, said shaft meanshaving an inherent resistance to deflection greater than said givenresistance, force transmitting means surrounding said shaft meansinwardly of the opposite ends thereof and bearing against the innersurface of said roll shell inwardly of the ends thereof, and movablefluid actuated means acting against the shaft portions outside the rollshell for selectively raising said shaft means and continuouslycounteracting said load to deflect said roll shell'generally centrallythereof through said force transmitting means and in opposition torestraint on the shell ends provided by said fixed bearings, wherebysaid given inherent resistance to deflection of the shell yieldssubstantially to the greater inherent resistance of said shaft means.

3. Apparatus comprising a roll shell having a given inherent resistanceto deflection and having in unloaded condition a straight-linecentroidal axis that develops normally a central deflection in responseto a load applied to the shell, load means acting against said rollshellnormally tending to effect-such deflection, fixed bearings rotatablymounting the ends of said roll shell, shaft means for the roll shellhaving shaft portions extending ou't wardly from the opposite endsthereof, said shaft means having an inherent resistance to deflectiongreater than said given resistance, force transmitting means surroundingsaid shaft means inwardly of the opposite ends thereof and in rigidassembly with the inner surface of said roll shell inwardly of the endsthereof, drive means for rotating the shaft means and the roll shellthereby, and movable fluid actuated'means acting against the shaftportions outside the roll shell for selectively raising said shaft meansand continuously counteracting said load to correct for the deflectionin the roll shell which said load means tends to effect generallycentrally thereof through said force transmitting means and inopposition to restraint on the shell ends provided by said fixedbearings, whereby said given inherent resistance to deflection of theshell yields substantially to the greater inherent resistance of saidshaft means.

4. Apparatus comprising, a roll shell having a given inherent resistanceto deflection and developing normally a central deflection in responseto a load applied thereto, fixed bearings rotatably mounting the ends ofsaid roll shell, shaft meansfor the roll shell having shaft portionsextending outwardly from the opposite ends thereof, said shaft meanshaving greater inherent resistance to deflection than said roll shell,force transmitting means sur- 5 rounding said shaft means at spacedlocations therealong and bearing against the inner surface of said rollshell inwardly of the opposite ends thereof and movable means forraising said shaft means to deflect said roll shell generally centrallythereof through said force transmitting means and in opposition to therestraint on the shell ends provided by said fixed bearings, saidmovable means being fluid pressure actuators acting against the shaftportions outwardly of the shell ends whereby the inherent resistance todeflection of the roll shell yields to the greater inherent resistanceto deflection of the shaft.

5. Apparatus comprising, a roll shell having a given inherent resistanceto deflection and normally a central deflection in response to a loadapplied to the shell, fixed bearings rotatably mounting said roll shell,shaft means for the roll shell having shaft portions extending outwardlyfrom the opposite ends thereof, said shaft means having an inherentresistance to deflection greater than said given resistance todeflection of the roll shell, second heating means rotatably mountingthe extended shaft portions, selfaligningbearing support means betweensaid shaft means and said roll shell inwardly of the opposite endsthereof and normally maintaining said shaft means and said shell incoaxi-ally spaced relation, and movablefluid actuators acting againstsaid second bearing means for selectively raising said shaft meansand-continuously counteracting said load to deflect said roll shellgenerally centrally thereof through said self-aligning bearing supportmeans and in opposition to restraint on the shell ends provided? by saidfixed bearings, whereby said given inherent resistance to deflection ofthe shell yields substantially to the greater inherent resistance ofsaid shaft means.

References Cited in the file of this patent UNITED STATES PATENTS GreatBritain May 3, 1929

1. APPARATUS COMPRISING, A ROLL SHELL HAVING NORMALLY A STRAIGHT LINECENTROIDAL AXIS THAT DEVELOPS NORMALLY, A CENTRAL DEFLECTION IN RESPONSETO A LOAD APPLIED TO THE SHELL, FIXED BEARINGS ROTATABLY MOUNTING THEENDS OF SAID ROLL SHELL, SHAFT MEANS FOR THE ROLL SHELL HAVING SHAFTPORTIONS EXTENDING OUTWARDLY FROM THE OPPOSITE ENDS THEREOF, SUPPORTMEANS BETWEEN SAID SHAFT MEANS AND SAID ROLL SHELL INWARDLY OF THEOPPOSITE ENDS THEREOF AND NORMALLY MAINTAINING SAID SHAFT MEANS AND SAIDSHELL IN COAXIALLY SPACED RELATION, AND MOVABLE FLUID ACTUATED RESILIENTMEANS FOR APPLYING A LIFTING FORCE TO EACH OF SAID SHAFT PORTIONS INOPPOSITION TO THE RESTRAINT ON SAID ROLL SHELL PROVIDED BY SAID FIXEDBEARINGS CONTINUOUSLY COUNTERACTING SAID LOAD TO RELIEVE THE NORMALDEFLECTION IN SAID SHELL, SAID ROLL SHELL HAVING A GIVEN INHERENTRESISTANCE TO DEFLECTION AND SAID SHAFT MEANS HAVING A SUBSTANTIALLYGREATER INHERENT RESISTANCE TO DEFLECTION, AND SAID GIVEN INHERENTRESISTANCE TO DEFLECTION OF THE SHELL YIELDING SUBSTANTIALLY TO SAIDGREATER INHERENT RESISTANCE OF THE SHAFT MEANS.